A free trade deal with Europe would be a "special opportunity" to send a message to the world, Australian Prime Minister Malcolm Turnbull says.

Amid concerns about protectionism in the United States under Donald Trump and populism in parts of Europe, Mr Turnbull will use a major speech in Germany tonight to declare a trade agreement would be about more than just pure economics.

He will say the deal is an opportunity for Australia and EU nations, led by Germany and France, to "show what we stand for, as well as what we stand against", at a time when the globe is facing more serious security challenges from countries like Russia that have shown "contempt for the rule of law".

"Political alienation is feeding populism and protectionism and providing opportunities for foreign interference," he will say, according to a draft of his address.

"The very same economic forces that have delivered prosperity and opportunity are also generating political uncertainty, military capability and strategic ambition."

Following the speech, the Prime Minister will meet German Chancellor Angela Merkel, a staunch free trade advocate, in the hope she will use her significant influence to help negotiations through the complex, lengthy processes of EU politics.

Agriculture, as expected, is looming as the big stumbling block with strong resistance being flagged in rural parts of France and Italy, as well as by some socialist and right-wing nationalist anti-free trade politicians.

But in his speech Mr Turnbull will make it clear that an agreement cannot be dominated or derailed by demands from European farming lobby groups.

He will say Australian farmers need better access to the massive European single market.

"The agreement must address the very restrictive farm tariffs and quotas that our farmers currently face," the draft speech says.

Mr Turnbull leaves Germany on Tuesday to visit Brussels, the EU capital and site of NATO headquarters, for more trade and security talks.

He will then attend Anzac Day commemorations on the western front in France before heading home.